fix quotient

sympy/printing/pretty/stringpict.py

@@ -115,7 +115,8 @@ def stack(*args, align="c"):
         from top to bottom.
         Returns string, baseline arguments for stringPict.
         The baseline is the baseline of the second picture.
-        Everything is centered.
+        By default, everything is centered. If `align` is set to
+        'l' ('r') the elements are aligned to the  left (right) margin.
         Baseline is the baseline of the second picture.
         Strings are allowed.
         The special value stringPict.LINE is a row of '-' extended to the width.
@@ -158,6 +159,7 @@ def stack(*args, align="c"):
             raise ValueError(
                 f"the align parameter must be one of 'l'(left), 'r'(right) or 'c' (center). Got {align}."
             )
+
         newBaseline = objects[0].height() + objects[1].baseline
         return "\n".join(newPicture), newBaseline
 
@@ -456,7 +458,7 @@ def __truediv__(self, den, slashed=False):
             den = den.parens()
 
         if num.binding == prettyForm.NEG:
-            num = num.right(' ')[0]
+            num = num.right(' ')
 
         return prettyForm(
             binding=prettyForm.DIV, *stringPict.stack(num, stringPict.LINE, den)